The present invention relates to a high-frequency heating apparatus, and more specifically to a high-frequency heating apparatus in which wave stirring means, e.g., a rotating waveguide, is provided in a heating chamber.
Recently there have been developed high-frequency heating apparatuses, such as microwave ovens, in which a rotating waveguide is rotatably disposed in a heating chamber so that high-frequency waves from the waveguide are introduced into the heating chamber to heat food therein.
The heating apparatuses of this type generally comprise an inner casing defining the heating chamber therein, and an excitation opening is formed in the top wall of the inner casing. A fixed waveguide is fixed on the top wall of the inner casing, having one end connected to the excitation opening and the other end to a magnetron. An electric motor is fixed on the fixed waveguide, and the rotating waveguide is located in the heating chamber so as to cover the excitation opening. The rotating waveguide is connected to the motor to be driven thereby. High-frequency waves emitted from the magnetron are fed into the rotating waveguide through the fixed waveguide and excitation opening and then radiated into the heating chamber.
The components, including the inner casing, motor, and magnetron, are housed in a cabinet. The height of the cabinet is determined on the basis of the sum of those of the inner casing, fixed waveguide, and motor. If the motor is set on the fixed waveguide as aforesaid, the height of the motor directly influences that of the cabinet, thus rendering the cabinet bulky. Accordingly, the prior art heating apparatuses of this type cannot meet the increasing demand for a compact design. Moreover, the bulky cabinet increases material cost. If the motor is on the fixed waveguide, furthermore, it must have a long driving shaft, resulting in a substantial vibration of the rotating waveguide during rotation. In this case, the rotating waveguide comes into contact with the inside of the inner casing, thereby causing noise or distortion of the rotating waveguide.